Apparatus for drying lumber



Jly 10, 1928., 1,676,552

H. L. HENDERSON -APPARATUS FOR DRYING LUMBER Filed Feb. 2l, 1927 Patented July 10, 1928.

UNITED srfras` HIRAM L. HENDERSON, F SYRACUSE, NEW YORK.`

APPARATUS FOR DRYING LUMBER.

Application med February 21, 1927. serial No. 169,852.

This invention relates to an apparatus for drying lumber and analogous uses 1n I which it is necessary to vent-ilate the mois-- ture laden air from the drying chamber 5 and to replace the same with fresh air which is preferably heated and moistened in transit to the drying chamber. c

This ventilation of the moisture laden air and influx of the 'fresh air together with l0 fthe supply of the necessary moisture is preferably regulated by suitable valves or dampers but owing to the widely fluctuating f" conditions of external atmospheric temperatures, humidities and air velocit-ies together l5 with the varying qualities, quantities, thicknesses and moisture content of diierent lkinds of lumber it is found to be commercially impracticable to maintain the proper drying conditions in the drying chamber by the manual operation of the dampers and valves.

The main object therefore of the present invention is to render these operations substantially automatic 'and dependent upon 5 the Atemperature and humidity of the air entering and leaving the kiln.

Another object is to provide means whereby a series of dampers controlling the ventilation and recirculation may be automatically and simultaneously operated from a single sourcev of power preferably by thermally controlled fluid pressure operated means.

A further Objectis to provide a mixing .chamber discharging into the heating chamber and provided with separate inlet ports communicating respectively with the drying chamber and with the atmosphere and cont-rolled by a single damper for regulating the recirculation of the air from the drying chamber to the heating chamber and also for regulating the amount of fresh air to be mixed with the recirculating air in transit to the heating chamber.

Another object is to operate the dampers in conjunction with a steam spraying or other moisture supplying device adapted to discharge into the outlet of the mixing or recirculating chamber in suchv manner that the dampers will close as the moisture sup ply increases and open as the moisture supply decreases, and thereby to automatically conserve the steam and at the same time to maintain more efficient and expeditious drying conditions in the drying chamber.

Other objects and uses will be brought out in the following description.

In the drawings Figures l and 2 are vertical sectional views of port-ions of a lumber drying kiln taken respectively on lines 1-1, Figure 2 and 2-2, Figure 1.

As illustrated, this kiln comprises a drylng3 chamber -A-, a heating chamber and a mixing chamber -C--, all incorporated within a suitable building structure -l-having a Ventilating stack -2--of any suitable height, not necessary to herein illustrate or describe.

The dryin lchamber .-A- and heating ychamber are disposed in horizontal planes one above the other and above the outlet of the mixingy chamber -C- so that the air heated in the heating chamber may pass by its own lighter specific gravity upwardly through and into contact with the material to be dried within the drying chamber.

his material such asy a pile or stack of lumber L is mounted upon a carriage -3- having wheels or rollers -4- adapted to travel upon the rails -5- of a track, i' said rails being supported upon horizontall partitions or floors -6- forming a part of the building structure -1- Suitable means is provided for heating the air in the chamber Bf for entrance into the bottom of the drying chamber -A-, said means consisting. in this in, stance, of a battery of steam pipe coils -7- which may be arranged in tiers one above the other uponl supporting members ,--8-, the latter being supported from the rails -5 by hangers 8-, Figure 2.

Steam lmay be supplied to the pipe coils -7- from any available source, not shown. The horizontal partition 6- is disposed in a plane substantially midway between the drying` chamber -A- and heating chamber -B- which chambers communicate 100 with each other through a .relatively large intervening opening.

The substructure of the drying chamber below the lhorizontal partition or floor -6-' is provided with a 'fresh air .inlet opening -9- communicating with the external at-` mosphere for permitting the inflow of fresh air into the mixing chamber C through a port l0- just below. the floor -6- and above the lower discharge end of the mixing chamber.

ings -14- on the frames -15 surround-v ing the Ventilating ports ll- This rock shaft extends through the outer wall of the building structure -V-- and is provided at its outer end with a crank arm -16- adapted to`be operated by a thermally controlled luid-pressure-operated device -17- through the medium of a connecting arm 18.

The mixing chamber --C- in addition to beingconnected throughthe port l0- .i

with the fresh air inlet -9- is also con'- nected by a port 19 to the drying chamber -A- whereby a part of the more or less moisture-laden air yin the drying chamber may pass into and through the mixing chamber and thence through an outlet conduit 20- into the heating chamber -B- below the heaters -7,-. Y

AA misture supplying device consists, in this instance, of a steam spray nozzle -21- mounted within the'conduit 20- to discharge steam through the open end of said A 1 This valve 23- is adapted to conduit into the lower portion of the heating chamber -B.

This steam moisture supplying nozzle -21- maybe connected to any available source of steam supply through the medium'- of a pipe -22- having a valve -23- at the exterior of the heating chamber. Y be opened and closed b a fluid-pressure-operated device -24 o any well-known construction.

chamber ,-A- with the 'mixing chamber C constitutes what may be termed a recirculating port which, together with the fresh air portv -1()--, is controlled by a damper 25- for regulating the mixture y of the fresh air with the recirculating air.

The valve 25- is operatively connected to and actuatedpby. the rock shaft 13- for simultaneous movement with the Ventilating damper l2-1v and is controlledby the same source of power such as the pressure operated device -l-L Y K The action ofthe fluid-pressure-operated devices -17- and 2li-is primarily and thermally controlled, preferably through the medium bf what Iis known as a wet bulb -26 to which water may be supplied .from any available source through a ,conduit .n so

so that when the air in the drying chambercontains an excessive amount of moisture its eect upon the wet bulb -26- will cause the simultaneous operation of both ofthe iuid-pressure-'operated devices V117 and- -24-- for opening the Ventilating valve ,--12dand fresh air valve -25- to allow the escape of the excess moisture laden air from the drying chamber through the sta-ck port -11- and to admita corresponding amount of fresh air through the port --10- into the mixing chamber where it mixes with a part of the recirculating vair from the drying chamber to take up a part of the moisture content atiwhich time the steam spray-controlling valve .-23- will have been opened to allow a jetrof steam to vbe projected with the mixture linto the heating chamber below the heating coils -7- after whichthe moistened air Vmixture will be heated and caused to circulate upwardly thru the material to be dried for additionally removing the moisture therefrom.

On the other hand, as the humidity of the -airin the drying chamber decreases its effect upon the wet bulb 2G- will allow partial collapse or retraction ofthe fluidpressure-operated devices -17 and -24- to proportionately close the dampers 712- and -425- across their respective ports l1- and -10 -and at the same timeto effect a corresponding closing of the steaml spray controlhng valve @Q3-.

As the Ventilating valve l2-.- and fresh air valve -25- are closing or closed the recircul'ating port -19-, which is always open, allows the air within thedrying chamber containing a safe or velicient moisture content to recirculate through the mixing chamber -C-.and thence through the conduit -20- into the heating chamber below the heating coils.

The wet bulb thermostat vor thermostats also automatically control the wet bulb'temperature by opening, closing or throttling the steam sprayers or jets -21-.

It will be understood -from the foregoing Y description that any number of Ventilating dampers as 12- and any number of fresh l air regulating dampers as -25- may be mounted upon and operated by the same rock shaft as -13- which isautomatically controlled through the medium of the Wet bulb F -26, thermostatic control -30- and luid-pressure-operated device -17- and that the Valve 23- controlling the extra steam moisture supply through the steam` nozzle 2lmay be controlled by the same wet bulb as -26- and thermostatic regulator -30, all of which serve to automatically regulate the temperature and humidity of the air in `the drying chamber by opening the fresh air and Ventilating dampers as the Wet bulbl temperature increases and to close said dampers when the Wet bulb decreases.

The recirculating air together with the steam admitted to the heating chamber through the conduit -20- ma be deflected upwardl from the open end o said conduit by a de ecting member -33- as shown in ,igure 2.

In a dry kiln having a drying chamber and a heating chamber communicating with each other through a recirculating passage having a fresh air inlet port, said drying chamber having a Ventilating port, separate dampers for said ports, a rock shaft connecting said dampers, llulid-pressure-operated means for rocking the shaft and thermallycontrolled means for varying the Huid-pres sure in said fluid-operated means.

In Witness whereof I have hereunto set my hand this 9th day of February, 1927.

HIRAM L.v HENDERSON. 

